For certain types of wireless communication, such as wireless communication that uses code division multiple access (CDMA), a mobile station may able to communicate with more than one sector of a wireless network for a communication session. For example, a mobile station may maintain an “active set” that identifies one or more sectors that the mobile station is currently using for a communication session. The mobile station may receive forward link signals for the communication session from the one or more sectors in the active set, and the same one or more sectors may receive the mobile station's reverse link signals for the communication session.
The active set may also change during a communication session. In a conventional “mobile assisted soft handoff procedure,” the mobile station measures the strengths of pilot signals transmitted by the sector(s) in the active set and the sector(s) in a “neighbor set.” If the pilot signal strength of a neighbor-set sector exceeds an add threshold, the mobile station may report this to the wireless network, e.g., by transmitting a Pilot Strength Measurement Message (PSMM), and the wireless network may instruct the mobile station to add the sector to its active set. The mobile station would then begin receiving forward link signals from the new active-set sector, and the new active-set sector would begin receiving the mobile station's reverse link signals. Conversely, if the pilot signal strength of an active-set sector falls below a drop threshold, the mobile station may report this to the wireless network (e.g., in a PSMM), and the wireless network may instruct the mobile station to drop the sector from its active set. The mobile station would then stop receiving forward link signals from the dropped sector, and the dropped sector would stop receiving the mobile station's reverse link signals.